The present invention relates to vacuum cleaners or vacuum sweepers in general, and more particularly to improvements in vacuum sweepers which are especially suited to collect borings produced by drilling tools in shops, factories or the like.
A drawback of presently known vacuum sweepers is that they produce excessive noise. Certain presently known attempts to reduce such noise include the provision of silencers or mufflers which are installed directly on the casing of the vacuum pump or blower or in a pipe through which the air stream issuing from the outlet of the pump escapes into the atmosphere. Such mufflers are rather complex, bulky and expensive, especially if their sound deadening effect is pronounced. Therefore, such mufflers failed to gain widespread acceptance in relatively small vacuum sweepers, for example, in portable vacuum sweepers for collection of borings or the like.